All of a sudden for no apparent reason, there's an ugly vertical separator in all my menus in firefox. This includes the 'right-click' context menu, the file menu, and the folders under bookmarks toolbar menu (see picture below). [http://img703.imageshack.us/img703/2641/problemt.jpg] The vertical separator overlaps the horizontal separator and its very ugly. There wasn't even a vertical separator when i ran firefox yesterday. Why did it suddenly appear and how do i remove it?